Representatives for Chastain, a 30-year-old California-born actress, and Ecosse Films, named as one of the movie's production companies, had no immediate comment about the report, which said the movie is set to be filmed in Pakistan, Angola, the South of France and Paris, where the princess died at age 36.

Diana, mother of the UK's Princes William and Harry and one of the most famous contemporary royal icons, and Khan, a native of Pakistan, met at a UK hospital in 1995. The princess had also visited Pakistan as part of her global charity work.

The two reportedly dated for two years until the early summer of 1997. She was then seen with businessman Dodi al-Fayed and the two were killed in a car crash in Paris that August after being chased by celebrity photographers. The princess' televised funeral was watched by more than 2.5 billion people.

Diana has been the subject of films before. Amy Seccombe and Anthony Zaki played Diana and Khan in the 1998 film "The People's Princess - A Tribute."

Toni Collette of "United States of Tara" played the princess in a 1997 movie called "Diana & Me," while Nathalie Brocker portrayed her in the 1997 film "The Murder of Princess Diana," which also starred Jennifer Morrison of the shows "House M.D." and "Once Upon a Time."